This project proposes to evaluate the implementation of the Diabetes Prevention Program (DPP) adapted to fit the unique characteristics of work organizations. Implementation research is an important step in the translation of research to practice because it examines how a set of intervention strategies can be used to integrate an evidence-based intervention within a specific setting, without the tightly controlled research infrastructure frequently associated with efficacy and effectiveness trials. DPP, which has been proven efficacious in clinical trials and effective in the worksite as well, is a 24 week weight management program designed to reduce caloric intake and increase caloric expenditure. The implementation of DPP in this study will be supported with strategies designed to bolster work and home environmental supports which, based on the ecological model and previous research, are key strategies for supporting health promotion programs in work settings. The corporate partner for the study will be Union Pacific Railroad (UPRR) which has very high levels of overweight and obesity that have been costly to the organization. Using a non-equivalent control group design, after matching sites, we will randomly assign four sites to treatment and control (n=1150 per condition). The primary outcome is BMI with secondary outcomes including healthy eating behaviors and physical activity levels. Other very important outcomes include changes in the work and home environmental supports, organizational measures measuring workplace improvement, and financial outcomes including health care utilization and ROI. Data will be collected at baseline, end of program, and six months post program. Statistical methods will be used to control for baseline differences and examine change over time. This study will not only provide the opportunity to test the implementation of a proven intervention in a high risk population, it will also enable us to test worksite specific implementation strategies (work and home environmental supports) about which there is considerable anecdotal, but little empirical evidence. This will provide valuable evidence on effective strategies for translating a proven intervention program to worksites. [unreadable] [unreadable] [unreadable] [unreadable]